The invention relates to an rpm regulator or rpm governor for fuel injection pumps of internal combustion engines. The present invention is concerned, more particularly, with an rpm regulator for annular slide-controlled injection pumps having a double-armed intermediate lever which is pivotable about an axis fixedly mounted in the housing, whose first lever arm is coupled with the delivery quantity adjusting member of the injection pump, and whose second lever arm, which is acted upon by an rpm signal indicator, is adjustable in accordance with the rpm against the force of at least one main regulating spring. The second lever arm supports on its free end an axis of rotation of a single-armed adjustment lever which is disposed between the intermediate lever and a drag lever subject to the force of the regulating spring. The adjustment lever is supported on the drag lever at a tilt point lying between its axis of rotation and the axis of the rpm signal indicator and the free end of the drag lever cooperates with an elastically yielding stop disposed between the axis of the rpm signal indicator and the axis of rotation of the intermediate lever. An rpm regulator of this type is known (DT-OS No. 24 02 372) in which the rpm signal indicator acts on the intermediate lever by means of the elastically yielding stop. As the rpm increase, the adjustment lever causes an increase in the fuel delivery quantity, i.e., a negative adjustment acting in a deregulating manner. A positive adjustment, wherein a decrease in the fuel delivery quantity is effected as the rpm increase, cannot be accomplished with this known regulator.
An rpm regulator of a similar construction is also known which is capable of causing a positive adjustment of the fuel delivery quantity. This regulator, however, which is otherwise structurally similar, has no adjustment lever, but rather the second lever arm of the intermediate lever is supported directly on the drag lever by means of an elastically yielding stop located on its free end. In this manner a positive adjustment can be attained. However, this regulator has the disadvantage in that the spring seat must perform relatively short control paths with small spring forces. The spring stroke and force are therefore difficult to adjust. This is especially disadvantageous when the annular slide of an annular slide-controlled distributing injection pump serves as the delivery quantity adjustment member. In this case, the activating paths and therefore the slide stroke for an adjustment are extremely small. In comparison with the adjustment control paths of about 1 mm for the regulating rod serving as the delivery quantity adjusting member in chamfer-controlled series injection pumps, slide strokes of only about 0.2 mm are required for the delivery of equally large quantity changes in slide-controlled distributing injection pumps. In order to be able to control such small adjustment strokes with sufficient precision, the largest possible transfer of the control path (adjustment strokes) of the delivery quantity adjusting member onto the stroke (adjustment control stroke) of the elastically yielding stop which determines the adjustment is necessary.